Thermally-isolated circuit elements have been developed and made in several ways. Reay et al. (U.S. Pat. No. 5,600,174) have shown that electrochemical etching of silicon can be used to create small masses of thermally-isolated silicon, in which circuit components could be housed. Such thermally-isolated circuit elements have the advantage that they can be heated independently of nearby circuit elements on the same chip or substrate. In this way, their operating temperature can be controlled independently without affecting the operation of other nearby circuit elements.
Grudin et al (WO2003/023794) have shown that resistors embedded in microstructures made of typical surface films used in integrated circuit fabrication processes, could enable thermal trimming of those resistors.
In electronics and microelectronics, especially analog electronics and microelectronics, the behavior of electronic components and circuits under conditions of varying temperatures is a very important topic. Circuit components are prone to significantly varying temperature coefficients with non-zero tolerances from as-manufactured specifications. As a result, electronic system designers, and analog microelectronics designers must take great efforts to design circuits to be relatively robust to temperature variations during operation.
Testing and characterization of the temperature behavior of such circuits in volume manufacturing or assembly is not trivial. Circuit parameters must be measured at room temperature, and also measured at least at one other temperature. Significant cost (time, resources) arises from the fact that the circuit must be heated and cooled, as well as stabilized at the measurement temperatures, and this typically consumes a significant amount of time.